Characterization of beta-cell specific function of isolated pancreatic islets from hyperglycemic C57BL/KsJ-db/db mice.

Isolated pancreatic islets from male hyperglycemic C57BL/KsJ-db/db mice were used to study (pro)insulin biosynthesis, insulin release and insulin content. A diminution of the insulin content to about 36% and of the insulin release (20 mmol/l glucose) to nearly one half was observed, whereas [3H]leucine incorporation into (pro)insulin was increased. Insulin biosynthesis as well as insulin release showed no further increase, when the glucose concentration was increased to 20 or 30 mmol/l. Cultivation of such islets in TCM 199 (10 mmol/l glucose or additionally increased [Mg++] to 5.3 mmol/l) for 48 h resulted in a significant increase of the insulin content and a restoration of the glucose dependent insulin release.